The active-matrix type liquid crystal display device is equipped with a liquid crystal layer held between a pair of substrates which counter mutually, and a display portion which consists of a plurality of display pixels arranged in the shape of a matrix. One of the pair of substrates includes scan lines arranged along row lines of the display pixels, and signal lines arranged along column lines of the display pixels in the matrix. An alignment state of the liquid crystal molecule contained in the liquid crystal layer is controlled by an electrical field impressed to the liquid crystal layer.
Recently, liquid crystal display devices such as an IPS (In-Plane Switching) mode type and a FFS (Fringe Field Switching) mode type using a lateral electrical field have been proposed. The IPS mode type and the FFS mode type include a plurality of first electrodes arranged in the matrix and a second electrode that corresponds to the first electrodes on one of the substrates, and the state of an alignment of the liquid crystal molecule contained in the liquid crystal layer is controlled by the lateral electrical field generated between the first and second electrodes.
In the liquid crystal display, a line inversion driving method is proposed, in which the polarity of the impressed voltage to the liquid crystal layer is inversed for every scan line for preventing generation of a flicker phenomenon. When the line inversion driving method is adopted in the IPS mode or the FFS mode, the second electrode is arranged for every scan line, and the voltage supplied to the second electrode for every one-frame period is changed to either of the high (H) level and the low (L) level to inverse the polarity of the voltage impressed to the liquid crystal layer. In this structure, the alignment of the liquid crystal molecule contained in the liquid crystal layer is controlled by the voltage supplied to the second electrode and a picture signal voltage sequentially written in the first electrode.
Here, when the resistance of the second electrode becomes large, the difference in potential might arise between a position near a signal input end and in a position apart from the signal input end of the second electrode, which may result in generation of a cross talk.
Conventionally, in Japanese Patent Application Laid Open No. p2008-180928, the FFS mode type liquid crystal display device is proposed, in which a plurality of contact holes to electrically connect the switching element with the pixel electrode, and the common wiring with the common electrode, respectively are formed by single process when the pixel electrode and the common electrode are formed on a planarizing layer.